From Muppet Wiki

Edgar Ott (1929-1994) was a German actor who took over the role of Cookie Monster on Sesamstrasse when Alexander Welbat died in 1977, and upon his own death, was succeeded by Welbat's son Douglas Welbat. Ott also dubbed the German voice of Earl Sinclair in Dinosaurs. Other credits included looping Telly Savalas in Kojak and various films, Bill Cosby in I Spy, and every Phil Harris character in a Disney animated feature (Baloo in The Jungle Book, Little John in Robin Hood, and O'Malley in The Aristocats).